Karen Darke watched the last Paralympics from her bed, laid up for a few weeks after damaging her skin during a month-long sea-kayaking adventure. "Watching telly in bed is not something I normally do," she says wryly – this is the woman who has handcycled across Japan, kayaked the Alaska coastline and skied across Greenland (not all of her achievements are physical: she also has a PhD in geology and has written two books – the latest, Boundless, will be out soon). "But the Paralympics happened to be on and handcycling was in it for the first time. Because I really like sport, I had thought before if there was anything I would like to compete in but nothing appealed. But when I saw the handcycling I thought that would be amazing, and how great to be at a home Games as well."

Darke started to train and entered the Paracycling World Cup in 2009. "Most people were there with their county teams, with mechanics and masseurs, and this was just me and my boyfriend with no idea what we were doing." She laughs. "I picked up bronze in two races there and British Cycling got in touch."

The training has been tough, she admits. "I've always been active so my base fitness was pretty good but I hadn't done any speed or intensity of effort. Gradually I got into doing that and my body adapted. I might only have to do some hard effort for five minutes, but at the time it feels like for ever, so sometimes I put my mind back to being in the middle of an icecap when you know you've got to ski for 10 hours a day and you might run out of food or water if you don't make that progress. That mental strength and discipline has helped me."

Darke became paralysed from the chest down after a climbing accident 20 years ago, when she was 21. She had already climbed Mont Blanc and the Matterhorn but her injury didn't stop her passion for the outdoors – since then, she has climbed El Capitan in the Yosemite valley, and next year will attempt to reach the south pole.

"People often say: 'Do you think you've done anything different,' and I can never answer that question because I don't know," she says. "Being in those places is about a love of the wilderness. That's no different from before, I just had to find new ways to do it. None of it has been about trying to prove anything."

At the Paralympics, she will compete in the road race – "it combines all the female handcycling categories together so I'll be racing against people who have more muscular function than I've got so it will be a bit more of a challenge" – and the time trial, in which she has a good chance of a medal. "I'm in the form of my life, I've trained really well and I just hope it's enough to do the British team proud."